JP5415821B2 - Substantially cylindrical powder molded body and powder molding die apparatus - Google Patents

Substantially cylindrical powder molded body and powder molding die apparatus Download PDF

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JP5415821B2
JP5415821B2 JP2009116504A JP2009116504A JP5415821B2 JP 5415821 B2 JP5415821 B2 JP 5415821B2 JP 2009116504 A JP2009116504 A JP 2009116504A JP 2009116504 A JP2009116504 A JP 2009116504A JP 5415821 B2 JP5415821 B2 JP 5415821B2
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curved
molded body
width
powder
basic circle
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JP2010265503A (en
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治郎 嶋
和則 前川
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Hitachi Powdered Metals Co Ltd
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Hitachi Powdered Metals Co Ltd
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Priority to JP2009116504A priority Critical patent/JP5415821B2/en
Priority to PCT/JP2010/058027 priority patent/WO2010131672A1/en
Priority to CN2010800207793A priority patent/CN102421553B/en
Priority to KR1020117027832A priority patent/KR101313521B1/en
Priority to US13/318,389 priority patent/US9174278B2/en
Priority to DE112010002732.3T priority patent/DE112010002732B4/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/12—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of wires
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • B22F3/03—Press-moulding apparatus therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
    • B30B11/007—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a plurality of pressing members working in different directions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
    • B30B11/02—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/02—Dies; Inserts therefor; Mounting thereof; Moulds
    • B30B15/022—Moulds for compacting material in powder, granular of pasta form
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/06—Platens or press rams
    • B30B15/065—Press rams
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2973—Particular cross section
    • Y10T428/2976—Longitudinally varying

Description

本発明は、主として金属粉末からなる原料粉末を金型の型孔に充填し、上下のパンチで圧縮成形して成形体を造形するといった粉末冶金法（いわゆる押型法）により製造される焼結機械部品に係わり、特に、断面が略円形である略円柱状成形体と、このような成形体を高密度に成形可能とする金型装置に関する。   The present invention relates to a sintering machine manufactured by a powder metallurgy method (so-called pressing method) in which a raw material powder mainly composed of metal powder is filled in a mold hole and is molded by compression molding with upper and lower punches. In particular, the present invention relates to a substantially cylindrical molded body having a substantially circular cross section, and a mold apparatus capable of molding such a molded body with high density.

上記粉末冶金法による焼結機械部品の製造方法は、（１）ニアネットシェイプに造形することができる、（２）大量生産に向く、（３）溶製材料では得られない特殊な材料を製造できる、等の特長を有するために、自動車用機械部品や各種産業用の機械部品に適用が進んでいる。   The powder metallurgy manufacturing method for sintered machine parts is as follows: (1) can be shaped into a near net shape, (2) suitable for mass production, (3) special materials that cannot be obtained with melted materials Since it has such features as being capable of being used, it has been applied to machine parts for automobiles and machine parts for various industries.

上記特長のうちの、とりわけ（３）の特長を活かしたものの１つに、点火コイル等の鉄心に用いられる圧粉磁心がある（特許文献１〜３等）。圧粉磁心は、一般に、鉄粉末等の軟磁性粉末の表面に絶縁被膜を設け、これに少量の樹脂粉末を添加して混合した混合粉を圧縮成形し、加熱処理して製造される。このような圧粉磁心においては、固有抵抗値が高いことから、使用時に発生する渦電流が軟磁性粉末の表面を被覆する絶縁被膜および樹脂によって軟磁性粉末の内部に閉じ込められるため、渦電流損が小さいという特性を有している。   Among the above features, in particular, one utilizing the feature (3) is a dust core used for an iron core such as an ignition coil (Patent Documents 1 to 3, etc.). In general, a dust core is manufactured by providing an insulating coating on the surface of a soft magnetic powder such as iron powder, compression-molding a mixed powder obtained by adding a small amount of resin powder to this, and subjecting it to a heat treatment. In such a dust core, since the specific resistance is high, the eddy current generated during use is confined inside the soft magnetic powder by the insulating coating and resin that covers the surface of the soft magnetic powder. Is small.

ところで、従来、鉄心等には積層珪素鋼板が用いられている。積層珪素鋼板は、電気抵抗を向上させる珪素を含有する珪素鋼板を結晶の容易磁化方向を圧延方向に揃えた方向性珪素鋼板とし、これを絶縁膜を介して複数積層させたものであって、固有抵抗値が高く、渦電流損が小さいという特性を有しており、このため、鉄心として広く用いられている。しかしながら、珪素鋼板は、硬く、造形性に乏しいため、小片に打ち抜いたものを積層して目的形状に造形されており、生産性の面では効率が低いという問題がある。この点、圧粉磁心は、上記（１）および（２）の特長を有することから、積層珪素鋼板に替わり適用が伸びている。   Conventionally, laminated silicon steel sheets have been used for iron cores and the like. The laminated silicon steel sheet is a directional silicon steel sheet containing silicon for improving electrical resistance and having the easy magnetization direction of the crystals aligned in the rolling direction, and a plurality of these are laminated via an insulating film, The specific resistance value is high and the eddy current loss is small. Therefore, it is widely used as an iron core. However, since silicon steel plates are hard and have poor formability, they are formed into target shapes by stacking punched pieces, and there is a problem that efficiency is low in terms of productivity. In this respect, since the dust core has the features (1) and (2), the application has been extended in place of the laminated silicon steel sheet.

点火コイル用の鉄心は、１次コイルと２次コイルに挿入されるが、これらコイルと鉄心との間には隙間がない状態において、磁気特性が最大限に発揮されることが知られている。したがって鉄心は、コイルの内径に応じた外径を有する断面円形の単純な円柱状のものが最適である。   It is known that the iron core for the ignition coil is inserted into the primary coil and the secondary coil, and the magnetic characteristics are exhibited to the maximum when there is no gap between the coil and the iron core. . Therefore, the iron core is optimally a simple cylindrical shape with a circular cross section having an outer diameter corresponding to the inner diameter of the coil.

単純な円柱状に原料粉末を成形する場合、一般的には、図１９（ａ）に示すように、ダイス２に形成された縦に延びる型孔２１と、この型孔２１に下側から摺動自在に挿入された下パンチ４とによって形成されるキャビティ（型孔２１の下パンチ４より上方部分）に適量の原料粉末を充填し、型孔２１に摺動自在に挿入される上パンチ３を上側から挿入し、上下のパンチ３，４によって原料粉末を圧縮するといった方法が採られている。この方法により、図１９（ｂ）に示すように、上下のパンチ３，４により端面１０が形成され、ダイス２の型孔２１の内周面により軸方向に延びる側面が形成された成形体１が得られる。すなわち、この成形方法は、円柱状の成形体を得るにあたり、粉末を成形体の軸方向に加圧する方法である。   When the raw material powder is formed into a simple columnar shape, generally, as shown in FIG. 19A, a vertically extending mold hole 21 formed in the die 2 and the mold hole 21 are slid from below. An appropriate amount of raw material powder is filled in a cavity (a portion above the lower punch 4 of the mold hole 21) formed by the lower punch 4 that is movably inserted, and the upper punch 3 that is slidably inserted into the mold hole 21. Is inserted from above, and the raw material powder is compressed by the upper and lower punches 3 and 4. By this method, as shown in FIG. 19B, the end surface 10 is formed by the upper and lower punches 3 and 4, and the molded body 1 in which the side surface extending in the axial direction is formed by the inner peripheral surface of the die hole 21 of the die 2 is formed. Is obtained. That is, this molding method is a method of pressing powder in the axial direction of the molded body in order to obtain a columnar molded body.

しかしながらこの方法では、成形体１における上下の端部（軸方向の両端部）ａの密度が中央部ｂの密度よりも高くなり、中央部ｂの密度が低くなるといった現象、すなわち、圧縮方向の中央部にいわゆるニュートラルゾーンが生じてしまう。このニュートラルゾーンは、上下のパンチ３，４で圧縮された粉末は圧力により粉末界面で滑って再配列されるとともに塑性変形して緻密化するが、上下のパンチ３，４から印加された圧力は端部ａから中央部ｂに向かって再配列および塑性変形により消費されつつ伝播するので、成形体１の端面１０からの距離が大きくなるにしたがい原料粉末に加わる圧力が減衰するといった理由で生じる。   However, in this method, the density of the upper and lower end portions (both end portions in the axial direction) a of the molded body 1 is higher than the density of the central portion b and the density of the central portion b is lowered, that is, in the compression direction. A so-called neutral zone occurs in the center. In this neutral zone, the powder compressed by the upper and lower punches 3 and 4 slides and rearranges at the powder interface due to pressure and is plastically deformed and densified, but the pressure applied from the upper and lower punches 3 and 4 is Propagating while being consumed by rearrangement and plastic deformation from the end portion a toward the central portion b, the pressure is applied to the raw material powder as the distance from the end face 10 of the molded body 1 increases.

ニュートラルゾーンの発生は、加圧面に対して圧縮方向の長さが長い成形体の場合には避けられないものであり、上下のパンチによる圧力を増大させても消失させることは難しい。上記鉄心用の圧粉磁心においては、特に磁束密度は軟磁性粉末の占積率に比例するため、密度の低いニュートラルゾーンが発生すると、その分、磁気特性が低下することとなるため、不都合である。   The generation of the neutral zone is unavoidable in the case of a molded body whose length in the compression direction is long with respect to the pressing surface, and it is difficult to eliminate even if the pressure by the upper and lower punches is increased. In the above-mentioned powder magnetic core for an iron core, since the magnetic flux density is proportional to the space factor of the soft magnetic powder, if a neutral zone with a low density is generated, the magnetic characteristics will be reduced accordingly. is there.

そこで、軸方向に長い略円柱状の成形体を圧縮成形するにあたり、成形体の軸方向に対して直交する径方向に粉末を圧縮する方法が提案されている（特許文献４，５等）。この方法によれば、圧縮方向の距離が短く、また、上下のパンチにより側面全体を押圧するため、ニュートラルゾーンを発生させることなく密度が長さ方向にわたって均一で、かつ、高い成形体を得ることができるとされている。   Therefore, a method has been proposed in which a powder is compressed in a radial direction perpendicular to the axial direction of the molded body when compressing a substantially cylindrical shaped body that is long in the axial direction (Patent Documents 4, 5, etc.). According to this method, since the distance in the compression direction is short and the entire side surface is pressed by the upper and lower punches, a molded body having a uniform density and a high density in the length direction can be obtained without generating a neutral zone. It is supposed to be possible.

特開平０３−２３８８０５号公報Japanese Patent Laid-Open No. 03-238805 特開２００６−２７８４９９号公報（請求項８）JP 2006-278499 A (Claim 8) 特開２００８−１５３６１１号公報JP 2008-153611 A 特公平０３−０１３２８１号公報Japanese Patent Publication No. 03-013211 特開２００５−２４００６０号公報JP-A-2005-240060

上記特許文献４，５に記載される成形方法は、図２０（ａ）に示すように、上下対称をなし、ダイス２の型孔２１に摺動自在に挿入される上下のパンチ３，４に形成された断面半円弧状の各パンチ面３１，４２間に粉末を充填して圧縮することにより、図２０（ｂ）および（ｃ）に示すように、上部円弧面１１と下部円弧面１２が形成された円柱状の成形体１を得るものである。しかしながらこの方法で用いられる上下のパンチ３，４は、圧縮成形時に互いに突き合わせられる状態となる幅方向両端の肉厚が薄いため、破損しやすいという不具合がある。   As shown in FIG. 20 (a), the molding methods described in Patent Documents 4 and 5 are vertically symmetrical, and are formed on the upper and lower punches 3 and 4 that are slidably inserted into the mold hole 21 of the die 2. As shown in FIGS. 20B and 20C, the upper arc surface 11 and the lower arc surface 12 are formed by filling and compressing the powder between the formed punch surfaces 31 and 42 having a semicircular arc cross section. The formed cylindrical shaped body 1 is obtained. However, the upper and lower punches 3 and 4 used in this method have a problem that they are easily damaged because the thickness at both ends in the width direction where they are brought into contact with each other during compression molding is thin.

この不具合を回避するため、薄肉となる幅方向両端部をカットした状態として一定以上の幅を有する平坦部３３，４３を形成している。また、これら平坦部３３，４３どうしが当接して破損することを防止するために、粉末を最後まで圧縮した状態でも、平坦部３３，４３の間がある程度離されている。このため、成形体１の側面には、平坦部３３，４３間で粉末が圧縮成形されてなる軸方向に延びる鍔部１３（図２０（ｃ）の斜線部）が突出することとなる。この鍔部１３は不要であるため機械加工によって除去され、成形体１は断面円形状に加工される。   In order to avoid this problem, the flat portions 33 and 43 having a certain width or more are formed in a state where both ends in the width direction that are thin are cut. Further, in order to prevent the flat portions 33 and 43 from coming into contact with each other and being damaged, the flat portions 33 and 43 are separated to some extent even when the powder is compressed to the end. For this reason, the flange 13 (shaded portion in FIG. 20C) extending in the axial direction formed by compression molding of the powder between the flat portions 33 and 43 protrudes on the side surface of the molded body 1. Since this flange 13 is unnecessary, it is removed by machining, and the molded body 1 is processed into a circular cross section.

すなわち上記特許文献４，５に記載される成形方法では、機械加工による鍔部１３の除去が必要であり、このことは、製造コストの増加を招くとともに、除去される部分の原料が無駄になるといった問題を生じさせることになる。そこで、鍔部１３を残したまま点火コイルの鉄心に用いることが考えられるが、その場合には、側面から突出する鍔部１３があることにより、コイルとの間の空隙が必然的に大きくなり、その分、磁気特性が低下することとなる。   That is, in the molding methods described in Patent Documents 4 and 5, it is necessary to remove the flange 13 by machining, which increases the manufacturing cost and wastes the raw material of the removed portion. It will cause the problem. Therefore, it is conceivable to use the iron core of the ignition coil with the flange 13 left, but in that case, the gap 13 between the coil inevitably increases due to the flange 13 protruding from the side surface. As a result, the magnetic properties are degraded.

よって本発明は、機械加工が不要であり、成形体のままで断面円形に近い形状の略円柱状成形体を提供することを目的としている。具体的には、目標とする断面形状が円（基礎円）の円柱に対して、体積比が０．９５以上となる形状の成形体を提供することを目的とする。また、このような形状の成形体を成形する金型装置を提供することを目的としている。   Accordingly, an object of the present invention is to provide a substantially cylindrical shaped body that does not require machining and has a shape close to a circular shape as it is. Specifically, an object of the present invention is to provide a molded body having a volume ratio of 0.95 or more with respect to a cylinder whose target cross-sectional shape is a circle (basic circle). Moreover, it aims at providing the metal mold | die apparatus which shape | molds the molded object of such a shape.

本発明の略円柱状の粉末成形体は、略円柱状を呈し、略円形状で該円形の軸心を中心とする基礎円に内接する断面外形を有する粉末成形体であって、前記断面外形は、少なくとも、該断面外形の軸心を挟む該軸心の両側の側面にそれぞれ形成され、前記基礎円から内側に延在する上パンチで形成される一対の側面縁部と、これら側面縁部の内側端部間をつなぎ、少なくとも上頂部が前記基礎円に内接する前記上パンチで形成される上部円弧面と、前記各側面縁部の外側端部間をつなぎ、少なくとも下頂部が前記基礎円に内接する下部円弧面とから構成されており、さらに、当該成形体の長さ方向の両端部には、前記各側面縁部から端面に向けて凹状に反りながら上昇して該端面に連なる前記上パンチで形成される湾曲した湾曲縁部と、各端面から側面にわたって、しだいに幅狭となりながら面取り状に湾曲形成された端部面取り部とが形成されていることを特徴とする。ここで、本発明においては、断面外形の各頂部が基礎円に対し０〜−０．５ｍｍの範囲に位置するものを内接したものとみなす。 The substantially cylindrical powder molded body of the present invention is a powder molded body having a substantially cylindrical shape, having a substantially circular shape and having a cross-sectional outer shape inscribed in a basic circle centered on the circular axis. Are formed on at least the side surfaces on both sides of the shaft center sandwiching the axis of the cross-sectional outer shape, and a pair of side edge portions formed by upper punches extending inward from the base circle, and these side edge portions The upper circular arc surface formed by the upper punch in which at least the upper top part is inscribed in the basic circle and the outer edge part of each side edge, and at least the lower top part is connected to the basic circle. are composed of a lower arcuate surface inscribed in, Furthermore, the both end portions in the longitudinal direction of the molded body, wherein said continuous to each side end face rises while warped in a concave shape toward the end face from the edge a curved curved edges are formed by the upper punch, the end faces Over Luo side, characterized in that the end chamfer is curved chamfered shape while becomes gradually narrow is formed. Here, in this invention, it is considered that each top part of a cross-sectional external shape is inscribed in the range of 0-0.5 mm with respect to a basic circle.

本発明の粉末成形体では、前記側面に、前記側面縁部に対して垂直に連続する側面平坦部が形成されている形態を含む。   The powder molded body of the present invention includes a form in which a side flat portion that is perpendicular to the side edge is formed on the side.

また、本発明の粉末成形体では、前記断面外形の前記下部円弧面が、前記基礎円に一致する中央下部円弧面と、該中央下部円弧面との間に形成された段差を介して該中央下部円弧面の両側に形成された側部下部円弧面とから構成されている形態を含む。   Further, in the powder molded body of the present invention, the lower circular arc surface of the cross-sectional outline is formed through the step formed between the central lower circular arc surface that coincides with the basic circle and the central lower circular arc surface. The form comprised from the side part lower circular arc surface formed in the both sides of a lower circular arc surface is included.

また、本発明の粉末成形体では、前記側面縁部の幅が０．１〜０．５ｍｍであり、前記湾曲縁部が、少なくとも１つの円弧面、楕円弧面、またはこれらの面が連続した複合面を呈し、該湾曲縁部の長さが１〜５ｍｍであるとともに、前記側面縁部からの上昇幅が１〜５ｍｍであり、前記端部面取り部の長さが前記湾曲縁部の長さ以上であって、該湾曲縁部の長さより２ｍｍ以下、かつ、湾曲縁部の端面への投影像が前記基礎円から外側に出ないように設定されていることを一具体例とする。 Further, in the powder molding of the present invention, the the width of the side edges 0.1 to 0.5 mm, the curved edge, at least one arcuate surface, an elliptical arc surface, or may have these surfaces continuous The curved edge has a length of 1 to 5 mm, the rising width from the side edge is 1 to 5 mm, and the end chamfered portion has a length of the curved edge. One specific example is that the length is equal to or longer than the length of the curved edge and 2 mm or less, and the projection image onto the end face of the curved edge is set so as not to protrude outward from the basic circle. .

さらに本発明の粉末成形体では、前記側面平坦部の高さが０を超え２ｍｍ以下であること、また、前記中央下部円弧面の幅が前記基礎円の直径の４０〜８０％であり、前記段差の高さが０を超え１ｍｍ以下であることを一具体例とする。   Furthermore, in the powder compact of the present invention, the height of the side flat portion is more than 0 and 2 mm or less, and the width of the central lower circular arc surface is 40 to 80% of the diameter of the basic circle, A specific example is that the height of the step is more than 0 and 1 mm or less.

次に、本発明の粉末成形金型装置は、上記本発明の粉末成形体を好適に製造し得るものであり、略円柱状を呈する粉末成形体を、軸方向に直交する方向に圧縮して成形する粉末成形金型装置であって、上下方向に貫通し、平面視略長方形状であり、上下方向中間部には、前記成形体の軸心を中心とする基礎円に近似する断面凹円弧状の段部が形成され、該段部の上側に幅方向寸法が比較的大きい幅大部が形成され、前記段部の下側に幅方向寸法が前記幅大部よりも小さい幅小部が形成され、長さ方向両端部に、端部に向かうにしたがって幅が小さくなる曲面部が形成された型孔を有するダイスと、前記型孔の前記幅小部に摺動自在に挿入され、上端面に、幅方向断面が前記基礎円に近似する凹円弧状の下パンチ面が形成された下パンチと、前記型孔の前記幅大部に摺動自在に挿入され、下端面に、幅方向断面が前記基礎円に一致もしくは近似する凹円弧状の上パンチ面が形成された上パンチとを備え、前記上パンチは、下端面の幅方向両端部に、上下方向に直交して、長さ方向に延びる平坦部が形成されており、長さ方向両端部に、前記平坦部から端面にわたって、下端面側からしだいに高さが湾曲しながら減少する湾曲面が形成され、さらに、前記ダイスの前記曲面部に対応した曲面部が形成されていることを特徴とする。   Next, the powder molding die apparatus of the present invention can suitably manufacture the powder molded body of the present invention, and compresses the powder molded body having a substantially cylindrical shape in a direction orthogonal to the axial direction. A powder molding die apparatus for molding, which is vertically concave and has a substantially rectangular shape in plan view, and an intermediate part in the vertical direction is a concave concave section that approximates a basic circle centered on the axis of the molded body An arc-shaped step portion is formed, a large-width portion having a relatively large width dimension is formed above the step portion, and a small-width portion having a width-direction dimension smaller than the large-width portion is formed below the step portion. A die having a mold hole formed at both ends in the length direction and having a curved surface portion whose width decreases toward the end, and is slidably inserted into the small width portion of the mold hole, A lower punch having a concave arc-shaped lower punch surface whose cross section in the width direction approximates to the basic circle is formed on the end surface; An upper punch that is slidably inserted into the large width portion of the mold hole and has a concave arc-shaped upper punch surface having a cross-section in the width direction matching or approximating the basic circle at the lower end surface, The punch is formed with flat portions extending in the length direction perpendicular to the vertical direction at both ends in the width direction of the lower end surface, and extending from the lower end surface side from the flat portion to the end surface at both ends in the length direction. A curved surface that gradually decreases in height while being curved is formed, and further, a curved surface portion corresponding to the curved surface portion of the die is formed.

上記本発明の金型装置においては、前記平坦部の幅が０．１〜０．５ｍｍであり、前記湾曲面が、少なくとも１つの円弧面、楕円弧面、またはこれらの面が連続した複合面を呈し、該湾曲面の長さが１〜５ｍｍであるとともに、前記平坦部からの上昇幅が１〜５ｍｍであり、前記曲面部の長さが前記湾曲面の長さ以上であって、該湾曲面の長さより２ｍｍ以下、かつ、湾曲面の端面への投影像が前記基礎円から外側に出ないように設定されている形態を含む。 In the mold apparatus of the present invention, the width of the flat portion is 0.1 to 0.5 mm, the curved surface, at least one arcuate surface, an elliptical arc surface, or may have these surfaces continuous composite Presenting a surface, the length of the curved surface is 1-5 mm, the rising width from the flat portion is 1-5 mm, and the length of the curved surface portion is equal to or greater than the length of the curved surface, It includes a mode in which the length of the curved surface is 2 mm or less and the projection image onto the end surface of the curved surface is set so as not to come out from the basic circle.

本発明の略円柱状の粉末成形体によれば、成形体のままで、目標とする円（基礎円）の円柱に対して体積比が０．９５以上となる形状の成形体となり得るから、機械加工が不要となり、製造コストの増加を抑制できるとともに、材料の無駄がなく、例えば、点火コイル用鉄心のための圧粉磁心に適用すると、円形のコイルと鉄心の空隙が極少となって鉄心の磁気特性を最大限に発揮できるようになるといった効果を奏する。   According to the substantially cylindrical powder molded body of the present invention, the molded body can be a molded body having a volume ratio of 0.95 or more with respect to a target circular (basic circle) cylinder as it is. Machining is not required, and the increase in manufacturing cost can be suppressed, and there is no waste of materials. For example, when applied to a dust core for an iron core for an ignition coil, the gap between the circular coil and the iron core is minimized. There is an effect that the magnetic properties of can be maximized.

本発明の第１実施形態に係る粉末成形体の（ａ）：端面図、（ｂ）：（ａ）のＡ部拡大図である。BRIEF DESCRIPTION OF THE DRAWINGS (a): End view of the powder compact which concerns on 1st Embodiment of this invention, (b): The A section enlarged view of (a). 第１実施形態の粉末成形体の斜視図である。It is a perspective view of the powder compact of a 1st embodiment. 第１実施形態の粉末成形体の（ａ）：側面図、（ｂ）：（ａ）のＢ部拡大図である。It is (a): side view of the powder compact of 1st Embodiment, (b): The B section enlarged view of (a). 第１実施形態の粉末成形体の（ａ）：上面図、（ｂ）：（ａ）のＣ部拡大図である。(A): Top view of powder compact of 1st Embodiment, (b): The C section enlarged view of (a). 第１実施形態の金型装置の上パンチを示す端面図である。It is an end elevation which shows the upper punch of the metal mold apparatus of 1st Embodiment. 第１実施形態の上パンチの斜視図である。It is a perspective view of the upper punch of a 1st embodiment. 第１実施形態の上パンチの（ａ）：側面図、（ｂ）：（ａ）のＤ部拡大図である。(A): Side view of upper punch of 1st Embodiment, (b): D section enlarged view of (a). 第１実施形態の上パンチの（ａ）：上面図、（ｂ）：（ａ）のＥ部拡大図である。(A): Top view of upper punch of 1st Embodiment, (b): E section enlarged view of (a). 第１実施形態の金型装置におけるダイスの（ａ）：上面図、（ｂ）：（ａ）のＦ部拡大図である。(A): Top view of the dice | dies in the metal mold apparatus of 1st Embodiment, (b): The F section enlarged view of (a). 第１実施形態の金型装置による粉末成形状態を示す断面図である。It is sectional drawing which shows the powder molding state by the metal mold apparatus of 1st Embodiment. 本発明の第２実施形態に係る金型装置による粉末成形状態を示す断面図である。It is sectional drawing which shows the powder molding state by the metal mold | die apparatus which concerns on 2nd Embodiment of this invention. 第２実施形態の粉末成形体の端面図である。It is an end view of the powder compact of a 2nd embodiment. 本発明の第３実施形態に係る粉末成形体の（ａ）：端部斜視図、（ｂ）：金型装置の上パンチの端部側面図である。(A): End part perspective view of the powder compact which concerns on 3rd Embodiment of this invention, (b): End part side view of the upper punch of a metal mold apparatus. 本発明の検討経過で用いた金型装置による粉末成形状態を示す断面図である。It is sectional drawing which shows the powder molding state by the metal mold apparatus used in progress of examination of this invention. 本発明の検討経過における粉末成形体の（ａ）：端面図、（ｂ）：斜視図である。It is (a): end elevation of powder compact in the progress of examination of the present invention, and (b): perspective view. 本発明の検討経過における金型装置の上パンチの斜視図である。It is a perspective view of the upper punch of the metal mold apparatus in the examination progress of the present invention. 第１実施形態に対する比較例における金型装置の上パンチの（ａ）：側面図、（ｂ）：斜視図である。It is (a): side view and (b): perspective view of the upper punch of the die apparatus in the comparative example with respect to the first embodiment. 第１実施形態に対する比較例の粉末成形体の（ａ）：端面図、（ｂ）：斜視図である。It is (a): end elevation of the powder compact of the comparative example with respect to 1st Embodiment, (b): It is a perspective view. （ａ）：円柱状の粉末成形体を圧縮成型する従来の一般的な成形金型装置の断面図、（ｂ）：（ａ）の金型装置で得られた粉末成形体の斜視図である。(A): Cross-sectional view of a conventional general mold apparatus for compression molding a cylindrical powder molded body, (b): A perspective view of a powder molded body obtained with the mold apparatus of (a). . （ａ）：円柱状の粉末成形体を圧縮成型する従来の成形金型装置の断面図、（ｂ）：（ａ）の金型装置で得られた粉末成形体の斜視図、（ｃ）：（ａ）の金型装置で得られた粉末成形体の端面図である。(A): Cross-sectional view of a conventional molding die apparatus for compression molding a cylindrical powder molded body, (b): Perspective view of a powder molded body obtained with the mold apparatus of (a), (c): It is an end elevation of the powder compact obtained with the metallic mold device of (a).

以下、図面を参照して本発明の実施形態を説明する。
［Ａ］本発明の検討経過
はじめに、本発明に至った検討経過を説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[A] Study progress of the present invention First, the study progress leading to the present invention will be described.

まず、最初に検討した粉末成形金型装置を図１４に、また、この金型装置により得られる粉末成形体（以下、成形体と略称）１Ａを図１５に示す。図１４の金型装置は、段付きのダイス２と、上下のパンチ３，４とを備える。ダイス２は、上下方向に貫通する型孔２１を有している。型孔２１は、平面視が成形体の長さ方向に応じた長方形状であり（図１４で図面表裏方向に長く延びている）、上下方向の中間部には、左右対称をなす段部２２が形成されている。段部２２は、基礎円Ｐ（目標とする円）に一致する断面凹円弧状に形成されている。型孔２１における段部２２の上方および下方は、それぞれ一定幅の幅大部２４ａ、幅小部２４ｂとなっている。そして、上パンチ３が幅大部２４ａに上方から摺動自在に挿入され、下パンチ４が幅小部２４ｂに下方から摺動自在に挿入されるようになっている。   First, FIG. 14 shows a powder molding die apparatus examined first, and FIG. 15 shows a powder molded body (hereinafter abbreviated as a molded body) 1A obtained by this mold apparatus. The mold apparatus of FIG. 14 includes a stepped die 2 and upper and lower punches 3 and 4. The die 2 has a mold hole 21 penetrating in the vertical direction. The mold hole 21 has a rectangular shape in plan view corresponding to the length direction of the molded body (extends in the drawing front and back direction in FIG. 14), and a stepped portion 22 that is symmetrical in the middle in the vertical direction. Is formed. The step portion 22 is formed in a concave arc shape in cross section that matches the basic circle P (target circle). The upper portion and the lower portion of the step portion 22 in the mold hole 21 are a large width portion 24a and a small width portion 24b having a constant width, respectively. The upper punch 3 is slidably inserted into the large width portion 24a from above, and the lower punch 4 is slidably inserted into the small width portion 24b from below.

下パンチ４の上端面には、基礎円Ｐに一致する単純な断面凹円弧状の下パンチ面４２が形成されている。圧縮成形時において下パンチ４は、下パンチ面４２が段部２２と同心状に一致する圧縮成形位置まで型孔２１の幅小部２４ｂに挿入される。   On the upper end surface of the lower punch 4, a lower punch surface 42 having a simple concave circular arc shape that coincides with the basic circle P is formed. At the time of compression molding, the lower punch 4 is inserted into the small width portion 24 b of the mold hole 21 until the compression molding position where the lower punch surface 42 coincides with the stepped portion 22.

上パンチ３の下端面には、基礎円Ｐに近似する円弧状の上パンチ面３１が形成されている。この上パンチ面３１の幅方向両端部には、上下方向に直交して長さ方向に延びる平坦部３５が形成されている。すなわち上パンチ面３１は、主たる上パンチ円弧面３１ａと、上パンチ円弧面３１ａの両側に延びる平坦部３５とから構成されている。平坦部３５は基礎円Ｐから内側に延びており、したがって上パンチ円弧面３１ａは基礎円Ｐよりも僅かに小径である。圧縮成形時において上パンチ３は、両側の平坦部３８と段部２２の上端との間に平坦面２４（幅大部の下端部）を空け、上頂部が基礎円Ｐの上頂部に重畳する圧縮成形位置まで型孔２１の幅大部２４ａに挿入される。   An arcuate upper punch surface 31 approximating the basic circle P is formed on the lower end surface of the upper punch 3. At both ends in the width direction of the upper punch surface 31, flat portions 35 extending in the length direction perpendicular to the vertical direction are formed. That is, the upper punch surface 31 includes a main upper punch arc surface 31a and flat portions 35 extending on both sides of the upper punch arc surface 31a. The flat portion 35 extends inward from the base circle P, and therefore the upper punch arc surface 31 a has a slightly smaller diameter than the base circle P. At the time of compression molding, the upper punch 3 has a flat surface 24 (the lower end portion of the large width portion) between the flat portions 38 on both sides and the upper end of the step portion 22, and the upper top portion overlaps the upper top portion of the basic circle P. Inserted into the large width portion 24a of the mold hole 21 up to the compression molding position.

上記構成からなる金型装置で成形体を得るには、まず、ダイス２の型孔２１の幅小部２４ｂに挿入されている下パンチ４を、上記圧縮成形位置よりもやや下側の位置に停止させ、上方に開口した型孔２１のキャビティに適量の原料粉末を充填する。次いで、下パンチ４を上記圧縮成形位置に上昇させるとともに、上パンチ３を上記圧縮成形位置まで下降させ、原料粉末を上下のパンチ３，４で圧縮する。圧縮後は、上パンチ３を上方に抜いて退避させ、下パンチ４を上昇させて成形体を脱型する。   In order to obtain a molded body with the mold apparatus having the above configuration, first, the lower punch 4 inserted in the narrow portion 24b of the die hole 21 of the die 2 is placed at a position slightly below the compression molding position. The cavity is stopped, and an appropriate amount of raw material powder is filled in the cavity of the mold cavity 21 opened upward. Next, the lower punch 4 is raised to the compression molding position, the upper punch 3 is lowered to the compression molding position, and the raw material powder is compressed by the upper and lower punches 3 and 4. After compression, the upper punch 3 is pulled upward and retracted, and the lower punch 4 is raised to remove the molded body.

このようにして得られる成形体１Ａは、図１５に示すように、下部円弧面１２は、ダイス２の両側の段部２２と下パンチ４の下パンチ面４２との連続面から形成されることから、基礎円Ｐに一致するものとなる。また、成形体１の側面には、上記平坦面２４により、長さ方向に延びる側面平坦部１４が形成されている。この側面平坦部１４は、側面縁部１５の外側端部１５ｃを上端とし、下端が下部円弧面１２に連なっている。また、成形体１の上部は、周方向に互いに略１８０°離れた上パンチ３の平坦部３５により形成される両側の上記側面縁部１５と、これら側面縁部１５の内側端部１５ｂ間をつなぐ上パンチ３の上パンチ円弧面３１により形成される上部円弧面１１を有するものとなる。   In the molded body 1A thus obtained, the lower circular arc surface 12 is formed from a continuous surface of the step portions 22 on both sides of the die 2 and the lower punch surface 42 of the lower punch 4 as shown in FIG. Therefore, it matches the basic circle P. A side flat portion 14 extending in the length direction is formed on the side surface of the molded body 1 by the flat surface 24. The side flat portion 14 has an outer end 15 c of the side edge 15 as an upper end and a lower end connected to the lower arc surface 12. Further, the upper portion of the molded body 1 is formed between the side edge portions 15 on both sides formed by the flat portions 35 of the upper punch 3 separated from each other by approximately 180 ° in the circumferential direction, and the inner end portions 15b of the side edge portions 15. It has the upper circular arc surface 11 formed by the upper punch arc surface 31 of the upper punch 3 to be connected.

この成形体１Ａは、次の利点がある。まず、側面縁部１５が基礎円Ｐの内側に延在しているため、基礎円Ｐを断面とする円柱に対する体積比が若干減少するものの、基礎円Ｐに近い、すなわち高い体積比を有する。また、下パンチ４においては、成形体１Ａの直径よりもかなり幅が小さいため、図２０（ａ）で示した下パンチ４のように両側の平坦部４３を形成する必要がない。一方、上パンチ３については平坦部３５が必要であるが、これを基礎円Ｐの内側に設けたことにより、図２０に示した基礎円Ｐの外部に突出する鍔部１３のようなものは形成されず、鍔部１３を除去する機械加工の必要がなくなる。   This molded body 1A has the following advantages. First, since the side edge 15 extends to the inside of the base circle P, the volume ratio with respect to the cylinder whose cross section is the base circle P is slightly reduced, but it is close to the base circle P, that is, has a high volume ratio. Further, since the width of the lower punch 4 is considerably smaller than the diameter of the molded body 1A, it is not necessary to form the flat portions 43 on both sides like the lower punch 4 shown in FIG. On the other hand, the flat portion 35 is required for the upper punch 3, but by providing this inside the basic circle P, the flange 13 protruding outside the basic circle P shown in FIG. It is not formed, and there is no need for machining to remove the flange 13.

ところで、鉄心用の圧粉磁心は、軟磁性粉末の占積率に比例して磁気特性が向上することから、成形圧力を高めることにより高密度の成形体を得るようにしている。このような状況の下で上記の金型装置を用い実際に成形を行ったところ、上パンチ３の平坦部３５の角部３９（図１６に示す）に欠けが発生した。この欠けは、平坦部３５が長さ方向に真っ直ぐ延びており、幅方向側からの支持がなされていないため、高荷重の下で角部３９に応力が集中することにより発生したものである。   By the way, since the magnetic characteristics of the powder magnetic core for the iron core are improved in proportion to the space factor of the soft magnetic powder, a high-density molded body is obtained by increasing the molding pressure. Under such circumstances, when the above mold apparatus was used for actual molding, chipping occurred in the corner 39 (shown in FIG. 16) of the flat portion 35 of the upper punch 3. The chipping occurs because the flat portion 35 extends straight in the length direction and is not supported from the width direction side, and stress is concentrated on the corner portion 39 under a high load.

［Ｂ］本発明の第１実施形態
本発明は上記の検討を踏まえてなされたものであり、以下に第１実施形態に係る成形体および金型装置について説明する。 [B] First Embodiment of the Present Invention The present invention has been made on the basis of the above examination, and a molded body and a mold apparatus according to the first embodiment will be described below.

図１〜図４は、第１実施形態の成形体１Ｂを示す図であり、図１は端面図、図２は斜視図、図３は側面図、図４は上面図である。また、図５〜図８は、第１実施形態の金型装置の上パンチ３の形状を示す図であり、図５は端面図、図６は斜視図、図７は側面図、図８は上面図である。また、図９は金型装置のダイスの上面図、図１０は金型装置の断面図である。   1-4 is a figure which shows the molded object 1B of 1st Embodiment, FIG. 1 is an end elevation, FIG. 2 is a perspective view, FIG. 3 is a side view, FIG. 4 is a top view. 5-8 is a figure which shows the shape of the upper punch 3 of the metal mold | die apparatus of 1st Embodiment, FIG. 5 is an end view, FIG. 6 is a perspective view, FIG. 7 is a side view, FIG. It is a top view. FIG. 9 is a top view of the die of the mold apparatus, and FIG. 10 is a cross-sectional view of the mold apparatus.

第１実施形態の成形体１Ｂは、上記の検討経過の成形体１Ａの技術思想により、従来例の鍔部１３をなくすとともに、新たな改良を追加することにより、検討経過において判明した上パンチ３の角部３９の欠け発生という課題を解決したものである。すなわち、
（１）成形体の断面外形が軸心を中心とする基礎円Ｐに内接すること、
（２）成形体の両側面に基礎円Ｐから内側に延在する側面縁部１５を形成すること、
（３）上部円弧面１１が、側面縁部１５の内側端部１５ｂ間にわたって形成され、少なくとも上頂部で基礎円Ｐに接すること、
（４）下部円弧面１２が、側面縁部１５の外側端部１５ｃ間にわたって形成され、少なくとも下頂部で基礎円Ｐに接すること、
については、上記の検討経過の成形体１Ａと共通している。
ここで、本発明においては、断面外形の各頂部が基礎円に対し０〜−０．５ｍｍの範囲に位置するものを内接したものとみなす。すなわち、工業生産上、寸法誤差が生じることはやむを得ないが、基礎円より断面がはみ出せば（すなわち＋となれば）、目標とするコイルの中空部に収容できず、その一方で、基礎円より小さすぎると、コイルとの間の空隙が大きくなってロスが増加するとともに、磁心の体積が減少して磁気特性が低下するからである。 The molded body 1B of the first embodiment is the upper punch 3 that has been found in the course of examination by eliminating the flange 13 of the conventional example and adding new improvements based on the technical idea of the molded body 1A in the course of examination described above. This solves the problem of occurrence of chipping of the corner portion 39. That is,
(1) The cross-sectional outer shape of the molded body is inscribed in a basic circle P centered on the axis,
(2) forming side edge portions 15 extending inward from the base circle P on both side surfaces of the molded body;
(3) The upper circular arc surface 11 is formed between the inner end portions 15b of the side edge 15 and is in contact with the basic circle P at least at the top.
(4) The lower circular arc surface 12 is formed between the outer end portions 15c of the side edge 15 and is in contact with the base circle P at least at the lower top portion;
Is common to the molded body 1A in the above-described examination process.
Here, in this invention, it is considered that each top part of a cross-sectional external shape is inscribed in the range of 0-0.5 mm with respect to a basic circle. In other words, it is inevitable that a dimensional error occurs in industrial production, but if the cross section protrudes from the basic circle (that is, if it becomes +), it cannot be accommodated in the hollow portion of the target coil. If it is too small, the gap between the coil and the coil increases, loss increases, the volume of the magnetic core decreases, and the magnetic properties deteriorate.

第１実施形態では、さらに、
（５）成形体の長さ方向両端部に、各側面縁部１５から端面１０に向けて凹状に反りながら上昇して端面１０に連なる凹状に湾曲した湾曲縁部１５ａを形成すること、
（６）成形体の長さ方向両端部に、各端面１０から側面にわたって、しだいに幅狭となりながら面取り状に湾曲形成された端部面取り部１６を形成すること、
といった要件を追加したものである。 In the first embodiment, further,
(5) Forming curved edge portions 15a that are curved in a concave shape continuous with the end surface 10 while rising in a concave shape from the side surface edge portions 15 toward the end surface 10 at both end portions in the length direction of the molded body,
(6) forming end chamfered portions 16 that are curved in a chamfered shape while gradually becoming narrower from both end surfaces 10 to the side surfaces at both ends in the length direction of the molded body;
These requirements are added.

上記（５）の要件は、上パンチ３の角部３９の欠けの課題を解決するための要件であり、成形体１Ｂの湾曲縁部１５ａは、上パンチ３の平坦部３５の長さ方向両端部に形成された湾曲面３５ａ（図５〜図８に示す）によって形成される。この湾曲面１５ａは、側面縁部１５から端面１０にわたって、下端面側からしだいに高さが湾曲しながら減少する凸面状に形成されている。このように、応力が集中して欠けが発生しやすかった角部３９（図１６参照）を応力が集中し難い湾曲面３５ａとすることで、応力の集中による欠けが効果的に防止される。   The requirement (5) is a requirement for solving the problem of chipping of the corner portion 39 of the upper punch 3, and the curved edge portion 15 a of the molded body 1 </ b> B has both ends in the length direction of the flat portion 35 of the upper punch 3. It is formed by a curved surface 35a (shown in FIGS. 5 to 8) formed in the portion. The curved surface 15a is formed in a convex shape from the side edge 15 to the end surface 10 so that the height gradually decreases while curving from the lower end surface side. As described above, the corner portion 39 (see FIG. 16) where stress is concentrated and the chipping is easily generated is the curved surface 35a where the stress is not easily concentrated, so that the chipping due to the stress concentration is effectively prevented.

次に、上記（６）の要件は、上記（５）の要件を追加した上で、成形体１Ｂの端面１０の形状を上記（１）の要件に合致させるために必要な要件であり、成形体１Ｂの端部面取り部１６は、図９に示すように、ダイス２の型孔２１の長さ方向両端部において、幅がしだいに縮小し、長さ方向に延びる側面２３から長さ方向両端部の端面２０に連なる曲面部２６を形成することで、形成される。また、上パンチ３は、ダイス２の型孔２１の曲面部２６に対応して、図５および図６に示すように、上パンチ３の長さ方向両端部において、幅がしだいに縮小し、端面３０に連なる凹面状の曲面部３６が形成される。これにより上パンチ３はダイス２の型孔２１と摺動自在に嵌合し、成形体１Ｂが成形可能となる。   Next, the requirement (6) is a requirement necessary for making the shape of the end face 10 of the molded body 1B conform to the requirement (1), after adding the requirement (5). As shown in FIG. 9, the end chamfered portions 16 of the body 1 </ b> B are gradually reduced in width at both ends in the mold hole 21 of the die 2, and both ends in the length direction from the side surfaces 23 extending in the length direction. It is formed by forming a curved surface portion 26 that continues to the end surface 20 of the portion. Further, as shown in FIGS. 5 and 6, the upper punch 3 gradually decreases in width at both ends in the length direction of the upper punch 3, corresponding to the curved surface portion 26 of the die hole 21 of the die 2. A concave curved surface portion 36 connected to the end surface 30 is formed. As a result, the upper punch 3 is slidably fitted into the mold hole 21 of the die 2 so that the molded body 1B can be molded.

ちなみに、上記要件（５）のみを適用し、上記要件（６）を適用しない場合、図１７に示すように、上パンチ３は、図１６に示した角部３９が湾曲面３５ａに形成されるため、上パンチ３の欠けの問題は解消される。図１７に示す上パンチ３を用いて成形した場合、図１８に示すように、成形体の両端部に、側面縁部１５から端面１０に向けて反りながら上昇して端面１０に連なる凹状に湾曲した湾曲縁部１５ａが形成される。ところが、この湾曲縁部１５ａを形成したことにより、端面１０の形状が基礎円Ｐより外側にはみ出す部分（図１８（ａ）の斜線部分）が生じてしまう。このはみ出し部分は、機械加工等により除去する必要が生じるため、本発明の課題は依然として残る。そこで第１実施形態では、上記要件（６）の端部面取り部１６を形成することにより、上記はみ出し部分を除去している。   Incidentally, when only the requirement (5) is applied and the requirement (6) is not applied, as shown in FIG. 17, the upper punch 3 is formed with the corner portion 39 shown in FIG. 16 on the curved surface 35a. Therefore, the problem of the upper punch 3 missing is solved. When the upper punch 3 shown in FIG. 17 is used for molding, as shown in FIG. 18, as shown in FIG. 18, the molded body rises while curving from the side edge 15 toward the end face 10 and is curved into a concave shape continuous to the end face 10. The curved edge portion 15a is formed. However, by forming the curved edge portion 15a, a portion (shaded portion in FIG. 18A) where the shape of the end face 10 protrudes outside the basic circle P is generated. Since this protruding part needs to be removed by machining or the like, the problem of the present invention still remains. Therefore, in the first embodiment, the protruding portion is removed by forming the end chamfered portion 16 having the requirement (6).

上記要件（５）の成形体１Ｂに形成される側面縁部１５は、そもそも上パンチ３の平坦部３５により形成されるものであって、上パンチ３の破損を防止するための結果として形成されるものである。この観点から、側面縁部１５の幅ｔ１（図１に示す）、すなわち上パンチ３の平坦部３５の幅ｔ１（図５に示す）は、少なくとも０．１ｍｍ以上とすることが好ましい。しかしながら、縁部１５の幅ｔ１が大きくなると、その分、基礎円Ｐに対して成形体１Ｂの断面積が減少する。このため、縁部１５の幅ｔ１は０．５ｍｍ以下とすることが好ましく、０．３ｍｍ以下とすることがさらに好ましい。   The side edge 15 formed in the molded body 1B of the above requirement (5) is originally formed by the flat portion 35 of the upper punch 3 and is formed as a result for preventing the upper punch 3 from being damaged. Is. From this viewpoint, it is preferable that the width t1 (shown in FIG. 1) of the side edge portion 15, that is, the width t1 (shown in FIG. 5) of the flat portion 35 of the upper punch 3 is at least 0.1 mm. However, when the width t1 of the edge 15 increases, the cross-sectional area of the molded body 1B decreases with respect to the basic circle P. For this reason, the width t1 of the edge 15 is preferably 0.5 mm or less, and more preferably 0.3 mm or less.

次に、上記要件（５）の成形体１Ｂの湾曲縁部１５ａは、上パンチ３の角部３９の欠けを防止するため、上パンチ３の湾曲面３５ａにより形成されるものである。この上パンチ３の湾曲面３５ａは、応力の集中を避けるため、上パンチ３の平坦部３５に連なる凹面状の円弧面もしくは楕円弧面とすることが好ましく、複数の円弧、楕円弧を滑らかに連続させて形成しても良い。図７に示すように、半径ｒ１の円弧で形成される上パンチ３の湾曲面３５ａは、短すぎると応力の集中を緩和できないことから、上パンチ３の長さ方向両端部の端面３０からの距離ｄ２、および上パンチ３の平坦部３５からの高さｄ３をいずれも１ｍｍ以上とすることが好ましい。   Next, the curved edge portion 15a of the molded body 1B having the above requirement (5) is formed by the curved surface 35a of the upper punch 3 in order to prevent the corner portion 39 of the upper punch 3 from being chipped. In order to avoid stress concentration, the curved surface 35a of the upper punch 3 is preferably a concave arc surface or an elliptical arc surface that is continuous with the flat portion 35 of the upper punch 3, and a plurality of arcs and elliptical arcs are continuously connected smoothly. May be formed. As shown in FIG. 7, the curved surface 35a of the upper punch 3 formed by an arc having a radius r1 cannot relax the stress concentration if it is too short. It is preferable that both the distance d2 and the height d3 from the flat portion 35 of the upper punch 3 are 1 mm or more.

また、図４に示すように、上記要件（６）の成形体１Ｂの端部面取り部１６の端面１０からの距離ｄ４は、成形体１Ｂの湾曲縁部１５ａに対応して形成されるため、大きすぎると成形体１Ｂの体積の減少率が増す。そこで、成形体１Ｂの湾曲縁部１５ａを形成する上パンチ３の湾曲面３５ａは、上パンチ３の長さ方向両端部の端面３０からの距離ｄ４（図８に示す）、および上パンチ３の平坦部３５からの高さｄ３（図７に示す）をいずれも５ｍｍ程度に抑えることが好ましい。すなわち、成形体１Ｂの湾曲縁部１５ａとしては、成形体１Ｂの端面１０からの距離ｄ２、および成形体１Ｂの側面縁部１５からの高さｄ３を１〜５ｍｍとし、上パンチ３の湾曲面３５ａとしては、上パンチ３の端面３０からの距離ｄ２、および上パンチ３の平坦部３５からの高さｄ３を１〜５ｍｍとすることが好ましい。 Moreover, as shown in FIG. 4 , since the distance d4 from the end surface 10 of the end chamfered portion 16 of the molded body 1B of the above requirement (6) is formed corresponding to the curved edge 15a of the molded body 1B, If it is too large, the volume reduction rate of the molded body 1B increases. Therefore, the curved surface 35a of the upper punch 3 forming the curved edge portion 15a of the molded body 1B has a distance d4 (shown in FIG. 8) from the end surfaces 30 at both ends in the length direction of the upper punch 3, and the upper punch 3 It is preferable to suppress the height d3 (shown in FIG. 7) from the flat portion 35 to about 5 mm. That is, as the curved edge 15a of the molded body 1B, the distance d2 from the end surface 10 of the molded body 1B and the height d3 from the side edge 15 of the molded body 1B are 1 to 5 mm, and the curved surface of the upper punch 3 As 35a, it is preferable that the distance d2 from the end face 30 of the upper punch 3 and the height d3 from the flat portion 35 of the upper punch 3 are 1 to 5 mm.

また、上パンチ３の湾曲面３５ａと上パンチ３の端面３０とを、円弧もしくは楕円弧で連続させると、端面付近３０で原料粉末が圧縮し難くなるため、図７（ｂ）に示すように、平坦部３５と平行な比較的短い平面部３５ｂを介して連続させることが好ましい。この平面部３５ｂの、上パンチ３の端面３０からの距離ｔ２は、大きすぎると湾曲面３５ａとの接続部で応力が集中しやすくなる。このため、上パンチ３の平面部３５ｂの端面３０からの距離ｔ２は、０を超え０．５ｍｍ以下、好ましくは０．１〜０．３ｍｍ程度とすることが好ましい。この上パンチ３の平面部３５ｂにより、成形体１Ｂには図３（ｂ）に示すように、端面１０と湾曲縁部１５ａとの間に長さｔ２の平面部１５ｂが形成されることとなる。   In addition, if the curved surface 35a of the upper punch 3 and the end surface 30 of the upper punch 3 are made continuous with an arc or an elliptical arc, the raw material powder becomes difficult to compress in the vicinity of the end surface 30, so as shown in FIG. It is preferable to continue through a relatively short flat part 35 b parallel to the flat part 35. If the distance t2 of the flat portion 35b from the end face 30 of the upper punch 3 is too large, stress tends to concentrate at the connecting portion with the curved surface 35a. For this reason, the distance t2 from the end face 30 of the flat portion 35b of the upper punch 3 exceeds 0 and is 0.5 mm or less, preferably about 0.1 to 0.3 mm. As shown in FIG. 3B, the flat portion 35b of the upper punch 3 forms a flat portion 15b having a length t2 between the end surface 10 and the curved edge portion 15a in the molded body 1B. .

次に、上記要件（６）の端部面取り部１６は、上記のように、成形体１Ｂに湾曲縁部１５ａを形成することにより、端面１０の形状が、基礎円Ｐから外側にはみ出すことを避けるために設けられるものである。このため、端部面取り部１６の端面１０からの距離ｄ４（図４（ｂ）に示す）は、少なくとも湾曲縁部１５ａの距離ｄ２（図２に示す）以上としなければならず、過大となるとそれに応じて成形体１Ｂの体積が減少することとなる。したがって距離ｄ４は距離ｄ２よりも２ｍｍ以下とすることが好ましく、ｄ２に一致させることが最も好ましい。   Next, the end chamfered portion 16 of the above requirement (6) is formed such that the shape of the end surface 10 protrudes outward from the base circle P by forming the curved edge portion 15a on the molded body 1B as described above. It is provided to avoid it. For this reason, the distance d4 (shown in FIG. 4B) from the end face 10 of the end chamfered portion 16 must be at least the distance d2 (shown in FIG. 2) of the curved edge portion 15a, which is excessive. Accordingly, the volume of the molded body 1B is reduced. Therefore, the distance d4 is preferably 2 mm or less than the distance d2, and most preferably coincides with d2.

また、成形体１Ｂの湾曲縁部１５ａは、側面縁部１５からしだいに高さが増して端面１０に連なるが、そこでの湾曲縁部１５ａの基礎円Ｐからのはみ出し量は湾曲縁部１５ａの高さに応じて決定される。したがって、端部面取り部１６における各部の幅の減少量ｄ５（図４（ｂ）に示す）は、湾曲縁部１５ａの高さの変化量に応じて決定され、湾曲縁部１５ａの端面１０への投影像が基礎円Ｐから外側にはみ出さないように設定される。   Further, the curved edge portion 15a of the molded body 1B gradually increases in height from the side edge portion 15 and continues to the end surface 10, but the amount of protrusion of the curved edge portion 15a from the basic circle P is that of the curved edge portion 15a. It is determined according to the height. Therefore, the width reduction amount d5 (shown in FIG. 4B) of each portion in the end chamfered portion 16 is determined according to the amount of change in the height of the curved edge portion 15a, and to the end surface 10 of the curved edge portion 15a. Is set so as not to protrude outward from the basic circle P.

このように形成される成形体１Ｂの端部面取り部１６は、ダイス２の型孔２１の曲面部２６、および上パンチ３の曲面部３６により形成されることから、ダイス２側の曲面部２６、および上パンチ３側の曲面部３６の距離ｄ４、これら曲面部２６，３６の幅の減少量ｄ５（図８（ｂ），図９（ｂ）に示す）は、成形体１の端面１０からの上記距離ｄ４、および端部面取り部１６の上記幅の減少量ｄ５に応じて決定される。   Since the end chamfered portion 16 of the molded body 1B formed in this way is formed by the curved surface portion 26 of the die hole 21 of the die 2 and the curved surface portion 36 of the upper punch 3, the curved surface portion 26 on the die 2 side. , And the distance d4 of the curved surface portion 36 on the upper punch 3 side and the amount of decrease d5 (shown in FIGS. 8B and 9B) of the curved surface portions 26 and 36 from the end surface 10 of the molded body 1. The distance d4 and the width reduction amount d5 of the end chamfered portion 16 are determined.

本実施形態の成形体１Ｂにおいて、軸心を通過する水平面に側面縁部１５を一致させ、この水平面で上部円弧面１１と下部円弧面１３とが等分に分割することが理想であるが、上パンチ３の平坦部３５と、ダイス２の段部２２が当接すると、上パンチが３の平坦部３５に欠けが生じやすくなることから、上パンチ３の平坦部３５と、ダイス２の段部２２をある程度離間させて成形を行うことが好ましい。このようにして成形すると、成形体１Ｂには、上記側面平坦部１４が形成されることになるが、これはやむを得ない。   In the molded body 1B of the present embodiment, it is ideal that the side edge 15 is aligned with the horizontal plane passing through the axis, and the upper arc surface 11 and the lower arc surface 13 are equally divided by this horizontal plane. When the flat portion 35 of the upper punch 3 and the step portion 22 of the die 2 come into contact with each other, the upper punch is likely to be chipped in the flat portion 35 of the die 3. It is preferable to perform the molding by separating the portions 22 to some extent. When it shape | molds in this way, the said side surface flat part 14 will be formed in the molded object 1B, but this is unavoidable.

ちなみにこの側面平坦部１４は、図１（ｂ）のように、基礎円Ｐの弦として、基礎円Ｐの内側に配置する必要がある。そのため、ダイス２の幅大部２４ａの幅は基礎円Ｐの径より若干小さい寸法に設定される。この側面平坦部１４の高さｄ１、すなわち上パンチ３の平坦部３５とダイス２の幅大部２４ａとの距離ｄ１（図１０に示す）は、大きくするとそれに応じて基礎円Ｐに対し成形体１Ｂの断面積が減少することとなる。このため、側面平坦部１４の高さｄ１は０を超え２ｍｍ以下とすることが好ましく、０を超え１ｍｍ以下とすることがさらに好ましい。   Incidentally, the side flat portion 14 needs to be arranged inside the base circle P as a chord of the base circle P as shown in FIG. Therefore, the width of the large width portion 24a of the die 2 is set to be slightly smaller than the diameter of the basic circle P. When the height d1 of the side flat portion 14, that is, the distance d1 (shown in FIG. 10) between the flat portion 35 of the upper punch 3 and the wide portion 24a of the die 2 is increased, the formed body with respect to the base circle P accordingly. The cross-sectional area of 1B will decrease. For this reason, the height d1 of the side flat portion 14 is preferably greater than 0 and 2 mm or less, and more preferably greater than 0 and 1 mm or less.

ダイス２の幅小部２４ｂに摺動自在に挿入される下パンチ４の幅Ｌ（図１０に示す）は、大きくすると下パンチ面４２と長さ方向に延びる側面４４がなす角度が小さくなって肉厚が薄くなるので、下パンチ４が破損するおそれが大きくなる。一方、下パンチ４の幅Ｌを小さくすると、成形に必要な量の原料粉末を充填するためにダイス２の幅小部２４ｂと下パンチ面４２とにより形成されるキャビティの深さを深くしなければならず、下パンチ４の長さを長くする必要が生じる。また、原料粉末は上パンチ３および下パンチ４で加圧されるが、下パンチ４の下パンチ面４２の面積が小さいと、原料粉末全体に下パンチ４からの加圧力を十分に伝達させることができず、原料粉末全体を良好に圧縮成形することが困難となる。さらに、下パンチ４の加圧力を大きくせざる得ず、長くした下パンチ４が折損するおそれが生じることとなる。このため、下パンチ４の幅Ｌは基礎円Ｐの４０〜８０％程度とすることが好ましい。   When the width L (shown in FIG. 10) of the lower punch 4 slidably inserted into the small width portion 24b of the die 2 is increased, the angle formed between the lower punch surface 42 and the side surface 44 extending in the length direction is decreased. Since the wall thickness is reduced, the possibility of damaging the lower punch 4 is increased. On the other hand, if the width L of the lower punch 4 is reduced, the depth of the cavity formed by the narrow portion 24b of the die 2 and the lower punch surface 42 must be increased in order to fill the raw material powder in an amount necessary for molding. Therefore, it is necessary to increase the length of the lower punch 4. The raw material powder is pressed by the upper punch 3 and the lower punch 4, but if the area of the lower punch surface 42 of the lower punch 4 is small, the applied pressure from the lower punch 4 can be sufficiently transmitted to the entire raw material powder. It is difficult to compress and mold the entire raw material powder. Furthermore, the pressurizing force of the lower punch 4 must be increased, and the longer lower punch 4 may be broken. For this reason, the width L of the lower punch 4 is preferably about 40 to 80% of the basic circle P.

上記本実施形態の成形体１Ｂにおいて、例えば、直径を１０ｍｍ、全長を８０ｍｍとし、側面平坦部１４の高さを１ｍｍ、側面縁部１５の幅を０．２ｍｍとするとともに、湾曲縁部１５ａを半径３ｍｍの円弧で形成し、かつ、湾曲縁部１５ａの距離ｄ２を３ｍｍ、湾曲縁部１５ａの高さｄ２を２ｍｍとした成形体１Ｂの体積は、６１９２ｍｍ３である。これに対し、直径が１０ｍｍ、全長が８０ｍｍの基礎円Ｐが断面である目標とする円柱の体積は６２８３ｍｍ３である。したがって本実施形態の成形体１Ｂは、目標円柱に対する体積比が０．９８６と高い体積比を示す。 In the molded body 1B of the present embodiment, for example, the diameter is 10 mm, the total length is 80 mm, the height of the side flat portion 14 is 1 mm, the width of the side edge 15 is 0.2 mm, and the curved edge 15a is formed. The volume of the molded body 1B formed by an arc having a radius of 3 mm, the distance d2 of the curved edge 15a being 3 mm, and the height d2 of the curved edge 15a being 2 mm is 6192 mm 3 . On the other hand, the volume of a target cylinder whose cross section is the basic circle P having a diameter of 10 mm and a total length of 80 mm is 6283 mm 3 . Therefore, the compact 1B of the present embodiment exhibits a high volume ratio of 0.986 with respect to the target cylinder.

［Ｃ］本発明の第２実施形態
次に、上記第１実施形態に基づく本発明の第２実施形態を説明する。
上記第１実施形態の成形体１Ｂは、下部円弧面１２が、ダイス２の段部２２と、下パンチ４の下パンチ面４２とから形成されるが、金型装置の組み付けにおいて、ダイス２の段部２２と、下パンチ面４２を完全に一致させることが難しい場合がある。そこで、図１１に示すように、ダイス２の段部２２の形状を、型孔２１の幅小部２４ｂに移行する箇所において基礎円Ｐよりも内側寄りの円弧面とし、高さｔ３の段差を設けて金型装置を組み立てるようにしても良い。 [C] Second Embodiment of the Present Invention Next, a second embodiment of the present invention based on the first embodiment will be described.
In the molded body 1B of the first embodiment, the lower circular arc surface 12 is formed from the step portion 22 of the die 2 and the lower punch surface 42 of the lower punch 4, but in the assembly of the mold apparatus, It may be difficult to completely match the step 22 and the lower punch surface 42. Therefore, as shown in FIG. 11, the shape of the step portion 22 of the die 2 is an arc surface closer to the inner side than the basic circle P at the position where the step portion 22b of the die hole 21 is shifted, and a step having a height t3 is formed. It may be provided to assemble the mold apparatus.

このように金型装置を組み立てると、ダイス２と下パンチ４の組み付け時の誤差を段差ｔ３で吸収することができ、組み付けが容易となる。しかしながら、段差ｔ３を設けると、それに応じて成形体の体積が減少することから、段差ｔ３は０を超え１ｍｍ以下とすることが好ましく、０を超え０．５ｍｍ以下とすることがさらに好ましい。   When the mold apparatus is assembled in this way, an error when the die 2 and the lower punch 4 are assembled can be absorbed by the step t3, and the assembly becomes easy. However, when the step t3 is provided, the volume of the molded body is reduced accordingly. Therefore, the step t3 is preferably more than 0 and 1 mm or less, and more preferably more than 0 and 0.5 mm or less.

また、下パンチ４は、下パンチ面４２と側面４４とがなす角部が尖鋭とはならないため破損し難いものの、加圧力を大きくすると欠けが生じるおそれはある。そのため、図１１に示すように、その角部に平面４７ａを設け、下パンチ面４２を、基礎円Ｐに一致する円弧面４７（元の下パンチ面４２の大部分）と、基礎円Ｐに接し基礎円Ｐの内側に短く延びる平面４７ａと、円弧面４７と平面４７ａとをつなぐ短い円弧面４７ｂとにより構成することが好ましい。しかしながら、平面４７ａを設けると、それに応じて成形体の体積が減少することから、平面４７ａの幅ｔ４は０を超え０．５ｍｍ以下、好ましくは０．１〜０．３ｍｍ以下とすることが好ましい。   Further, the lower punch 4 is not easily damaged because the corner formed by the lower punch surface 42 and the side surface 44 is not sharp, but there is a possibility that chipping may occur when the applied pressure is increased. Therefore, as shown in FIG. 11, a flat surface 47 a is provided at the corner, and the lower punch surface 42 is formed on an arc surface 47 (most part of the original lower punch surface 42) coincident with the basic circle P and the basic circle P. It is preferable to configure the flat surface 47a that extends shortly inside the contact basic circle P and the short circular arc surface 47b that connects the circular arc surface 47 and the flat surface 47a. However, if the flat surface 47a is provided, the volume of the molded body is reduced accordingly. Therefore, the width t4 of the flat surface 47a exceeds 0 and is 0.5 mm or less, preferably 0.1 to 0.3 mm or less. .

図１２は、上記のようにダイス２と下パンチ４との間に段差ｔ３を設け、下パンチ４に幅ｔ４の平面４７ａを設けた金型装置により成形される成形体１Ｃを示しており、段差ｔ３により段差１７ａが形成されている。この成形体１Ｃの下部円弧面１２は、段差１７ａ間の中央下部円弧面１２ａと、段差１７ａを介して中央下部円弧面１２ａの両側に形成された側部下部円弧面１２ｂとから構成されている。ここで、上記により体積計算した第２実施形態の成形体１Ｃの形状に、段差１７ａの高さｔ３を０．２ｍｍ、平面４７ａの幅ｔ４を０．２ｍｍの条件を付加した場合の成形体１の体積は６１４６ｍｍ３であり、目標とする円柱の体積（６２８３ｍｍ３）に対し、体積比が０．９７８と高い体積比を示す。 FIG. 12 shows a molded body 1C formed by a mold apparatus in which a step t3 is provided between the die 2 and the lower punch 4 as described above, and a flat surface 47a having a width t4 is provided on the lower punch 4. A step 17a is formed by the step t3. The lower circular arc surface 12 of the molded body 1C is composed of a central lower circular arc surface 12a between the steps 17a and side lower circular arc surfaces 12b formed on both sides of the central lower circular surface 12a via the step 17a. . Here, the molded body 1 in the case where the condition that the height t3 of the step 17a is 0.2 mm and the width t4 of the flat surface 47a is 0.2 mm is added to the shape of the molded body 1C of the second embodiment which has been volume-calculated as described above. The volume is 6146 mm 3 , and the volume ratio is as high as 0.978 with respect to the target cylinder volume (6283 mm 3 ).

［Ｄ］本発明の第３実施形態
次に、上記第１実施形態に基づく本発明の第３実施形態を説明する。
第１実施形態の成形体１において、図１３（ａ）に示すように、端面１０と上部円弧面１１とを滑らかな凸面状の曲面１１ａを介して連続させると、この部分の密度が向上しやすくなるため好ましい。曲面１１ａは、図１３（ｂ）のように、上パンチ３の上パンチ円弧面３１から上パンチ３の端面３０にわたって形成された曲面３１ａにより形成される。 [D] Third Embodiment of the Present Invention Next, a third embodiment of the present invention based on the first embodiment will be described.
In the molded body 1 of the first embodiment, as shown in FIG. 13A, when the end face 10 and the upper circular arc surface 11 are continued via a smooth convex curved surface 11a, the density of this portion is improved. Since it becomes easy, it is preferable. The curved surface 11 a is formed by a curved surface 31 a formed from the upper punch arc surface 31 of the upper punch 3 to the end surface 30 of the upper punch 3 as shown in FIG.

この第３実施形態の成形体１Ｄにおいて、半径１ｍｍの滑らかな曲面１１ａを形成したものの体積は６１８８ｍｍ３であり、目標とする円柱の体積（６２８３ｍｍ３）に対し、体積比が０．９８５と高い体積比を示す。また、上記第２実施形態の成形体１Ｃに半径１ｍｍの滑らかな曲面１１ａを形成したものの体積は６１４２ｍｍ３であり、目標とする円柱の体積（６２８３ｍｍ３）に対し、体積比が０．９７７と高い体積比を示す。 In the molded body 1D of the third embodiment, the volume of the smooth curved surface 11a having a radius of 1 mm is 6188 mm 3 , and the volume ratio is as high as 0.985 with respect to the target cylindrical volume (6283 mm 3 ). The volume ratio is shown. The volume of the smooth curved surface 11a having a radius of 1 mm formed on the molded body 1C of the second embodiment is 6142 mm 3 , and the volume ratio is 0.977 with respect to the target cylinder volume (6283 mm 3 ). A high volume ratio is shown.

本発明によれば、ニュートラルゾーンがなく、機械加工が不要であり、成形体のままで断面円形に近い形状の略円柱状の粉末成形体を提供することができるので、このような粉末成形体を低コストで製造することができる。したがって本発明による粉末成形体は、各種円筒形状部品、特に、鉄心用の圧粉磁心に好適なものである。   According to the present invention, since there is no neutral zone, machining is not required, and a substantially cylindrical powder molded body having a shape close to a circular shape can be provided as a molded body, such a powder molded body can be provided. Can be manufactured at low cost. Therefore, the powder molded body according to the present invention is suitable for various cylindrical parts, particularly, a dust core for an iron core.

１Ｂ，１Ｃ，１Ｄ…粉末成形体
１０…成形体の端面
１１…上部円弧面
１２…下部円弧面
１２ａ…中央下部円弧面
１２ｂ…側部下部円弧面
１４…側面平坦部
１５…側面縁部
１５ａ…湾曲縁部
１５ｂ…側面縁部の内側端部
１５ｃ…側面縁部の外側端部
１６…端部面取り部
２…ダイス
２１…型孔
２２…段部
２４ａ…型孔の幅大部
２４ｂ…型孔の幅小部
２６…ダイスの曲面部
３…上パンチ
３０…上パンチの端面
３１…上パンチ面
３５…平坦部
３５ａ…上パンチの湾曲面
３６…上パンチの曲面部
４…下パンチ
４２…下パンチ面
Ｐ…基礎円 DESCRIPTION OF SYMBOLS 1B, 1C, 1D ... Powder molded object 10 ... End surface of a molded object 11 ... Upper circular arc surface 12 ... Lower circular arc surface 12a ... Central lower circular arc surface 12b ... Side part lower circular arc surface 14 ... Side flat part 15 ... Side edge 15a ... Curved edge 15b ... Inner end of side edge 15c ... Outer end of side edge 16 ... End chamfer 2 ... Dies 21 ... Mold hole 22 ... Step part 24a ... Wide part of mold hole 24b ... Mold hole 26 ... The curved surface portion of the die 3 ... The upper punch 30 ... The end surface of the upper punch 31 ... The upper punch surface 35 ... The flat portion 35a ... The curved surface surface of the upper punch 36 ... The curved surface portion of the upper punch 4 ... The lower punch 42 ... Lower Punch surface P ... Basic circle

Claims (8)

略円柱状を呈し、略円形状で該円形の軸心を中心とする基礎円に内接する断面外形を有する粉末成形体であって、
前記断面外形は、少なくとも、
該断面外形の軸心を挟む該軸心の両側の側面にそれぞれ形成され、前記基礎円から内側に延在する上パンチで形成される一対の側面縁部と、
これら側面縁部の内側端部間をつなぎ、少なくとも上頂部が前記基礎円に内接する前記上パンチで形成される上部円弧面と、
前記各側面縁部の外側端部間をつなぎ、少なくとも下頂部が前記基礎円に内接する下部円弧面と、から構成されており、
さらに、当該成形体の長さ方向の両端部には、
前記各側面縁部から端面に向けて凹状に反りながら上昇して該端面に連なる前記上パンチで形成される湾曲した湾曲縁部と、
各端面から側面にわたって、しだいに幅狭となりながら面取り状に湾曲形成された端部面取り部とが形成されていることを特徴とする略円柱状の粉末成形体。 A powder molded body having a substantially cylindrical shape, having a substantially circular shape and a cross-sectional outer shape inscribed in a basic circle centered on the circular axis,
The cross-sectional profile is at least
A pair of side edges formed by upper punches that are respectively formed on both side surfaces of the shaft center across the shaft center of the cross-sectional outer shape and extend inward from the base circle;
An upper arc surface formed by the upper punch that connects between the inner ends of the side edge portions and at least an upper top portion is inscribed in the basic circle;
A lower circular arc surface that connects between the outer end portions of the side edge portions, and at least a lower top portion is inscribed in the basic circle, and
Furthermore, at both ends in the length direction of the molded body,
A curved curved edge formed by the upper punch that rises while curving in a concave shape from each side edge to the end face and continues to the end face;
A substantially cylindrical powder compact characterized in that an end chamfered portion that is curved in a chamfered shape while gradually becoming narrower is formed from each end surface to the side surface. 前記側面に、前記側面縁部に対して垂直に連続する側面平坦部が形成されていることを特徴とする請求項１に記載の略円柱状の粉末成形体。   The substantially cylindrical powder compact according to claim 1, wherein a side flat portion that is perpendicular to the side edge is formed on the side surface. 前記断面外形の前記下部円弧面が、前記基礎円に一致する中央下部円弧面と、該中央下部円弧面との間に形成された段差を介して該中央下部円弧面の両側に形成された側部下部円弧面とから構成されていることを特徴とする請求項１または２に記載の略円柱状の成形体。   The side where the lower circular arc surface of the cross-sectional outline is formed on both sides of the central lower circular arc surface through a step formed between the central lower circular arc surface coinciding with the basic circle and the central lower circular arc surface The substantially cylindrical shaped body according to claim 1, wherein the substantially cylindrical shaped body is configured by a lower circular arc surface. 前記側面縁部の幅が０．１〜０．５ｍｍであり、
前記湾曲縁部が、少なくとも１つの円弧面、楕円弧面、またはこれらの面が連続した複合面を呈し、該湾曲縁部の長さが１〜５ｍｍであるとともに、前記側面縁部からの上昇幅が１〜５ｍｍであり、
前記端部面取り部の長さが前記湾曲縁部の長さ以上であって、該湾曲縁部の長さより２ｍｍ以下、かつ、湾曲縁部の端面への投影像が前記基礎円から外側に出ないように設定されていることを特徴とする請求項１〜３のいずれかに記載の略円柱状の粉末成形体。 The width of the side edge is 0.1 to 0.5 mm,
The curved edges, at least one arcuate surface, an elliptical arc surface, or exhibits a composite surface in which these surfaces are continuous, with the length of the curved edge is 1 to 5 mm, from the side edges The rising width is 1-5 mm,
The length of the end chamfered portion is equal to or longer than the length of the curved edge portion, 2 mm or less than the length of the curved edge portion, and a projected image on the end surface of the curved edge portion protrudes outward from the basic circle. It is set so that it may not exist, The substantially cylindrical powder molded object in any one of Claims 1-3 characterized by the above-mentioned. 前記側面平坦部の高さが０を超え２ｍｍ以下であることを特徴とする請求項２に記載の略円柱状の粉末成形体。   The substantially cylindrical powder compact according to claim 2, wherein the height of the side flat portion is greater than 0 and 2 mm or less. 前記中央下部円弧面の幅が前記基礎円の直径の４０〜８０％であり、
前記段差の高さが０を超え１ｍｍ以下であることを特徴とする請求項３に記載の略円柱状の粉末成形体。 The width of the central lower arc surface is 40 to 80% of the diameter of the base circle;
The substantially cylindrical powder compact according to claim 3, wherein the height of the step is greater than 0 and 1 mm or less. 略円柱状を呈する粉末成形体を、軸方向に直交する方向に圧縮して成形する粉末成形金型装置であって、
上下方向に貫通し、平面視略長方形状であり、上下方向中間部には、前記成形体の軸心を中心とする基礎円に近似する断面凹円弧状の段部が形成され、該段部の上側に幅方向寸法が比較的大きい幅大部が形成され、
前記段部の下側に幅方向寸法が前記幅大部よりも小さい幅小部が形成され、
長さ方向両端部に、端部に向かうにしたがって幅が小さくなる曲面部が形成された型孔を有するダイスと、
前記型孔の前記幅小部に摺動自在に挿入され、上端面に、幅方向断面が前記基礎円に近似する凹円弧状の下パンチ面が形成された下パンチと、
前記型孔の前記幅大部に摺動自在に挿入され、
下端面に、幅方向断面が前記基礎円に一致もしくは近似する凹円弧状の上パンチ面が形成された上パンチとを備え、
前記上パンチは、
下端面の幅方向両端部に、上下方向に直交して、長さ方向に延びる平坦部が形成されており、長さ方向両端部に、前記平坦部から端面にわたって、下端面側からしだいに高さが湾曲しながら減少する湾曲面が形成され、さらに、前記ダイスの前記曲面部に対応した曲面部が形成されていることを特徴とする粉末成形金型装置。 A powder molding die apparatus that compresses and molds a powder molded body exhibiting a substantially cylindrical shape in a direction orthogonal to the axial direction,
A stepped part having a concave arc shape in cross section that approximates a basic circle centered on the axis of the molded body is formed in the intermediate part in the vertical direction, penetrating in the vertical direction and having a substantially rectangular shape in plan view. A large width portion having a relatively large width direction dimension is formed on the upper side,
A small width portion having a width dimension smaller than the large width portion is formed below the stepped portion,
A die having a mold hole in which a curved surface portion whose width decreases toward the end portion is formed at both ends in the length direction;
A lower punch, which is slidably inserted into the small width portion of the mold cavity, and has a concave arc-shaped lower punch surface whose width direction cross section approximates the basic circle on the upper end surface;
Slidably inserted into the wide part of the mold cavity,
An upper punch on which a concave arc-shaped upper punch surface whose cross-section in the width direction matches or approximates the basic circle is formed on the lower end surface;
The upper punch is
Flat portions extending in the length direction perpendicular to the vertical direction are formed at both end portions in the width direction of the lower end surface, and gradually increase from the lower end surface side from the flat portion to the end surface at both end portions in the length direction. A powder molding die apparatus, wherein a curved surface that decreases while being curved is formed, and further, a curved surface portion corresponding to the curved surface portion of the die is formed. 前記平坦部の幅が０．１〜０．５ｍｍであり、
前記湾曲面が、少なくとも１つの円弧面、楕円弧面、またはこれらの面が連続した複合面を呈し、該湾曲面の長さが１〜５ｍｍであるとともに、前記平坦部からの上昇幅が１〜５ｍｍであり、
前記曲面部の長さが前記湾曲面の長さ以上であって、該湾曲面の長さより２ｍｍ以下、かつ、湾曲面の端面への投影像が前記基礎円から外側に出ないように設定されていることを特徴とする請求項７に記載の粉末成形金型装置。 The flat portion has a width of 0.1 to 0.5 mm,
The curved surface, at least one arcuate surface, an elliptical arc surface, or exhibits a composite surface in which these surfaces are continuous, with the length of該湾curved surface is 1 to 5 mm, the rise from the flat portion 1-5 mm,
The length of the curved surface portion is not less than the length of the curved surface, 2 mm or less than the length of the curved surface, and is set so that the projected image on the end surface of the curved surface does not come out from the basic circle. The powder molding die apparatus according to claim 7, wherein
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